Abstract
South Africa's transition to renewable energy sources (RES), particularly solar photovoltaics (PV), requires robust energy storage solutions to counterbalance intermittency and meet low-carbon objectives. This study offers a comparative techno-economic analysis of three large-scale battery energy storage systems (BESS): lithium iron phosphate (LFP), lead-acid (Pb-acid), and vanadium redox flow batteries (VRFB). These technologies were selected for technical maturity, cost-effectiveness, and suitability in stationary applications. Using HOMER Pro software, two BESS capacity scenarios A (1.17 MWh) and B (2.34 MWh) were simulated and evaluated on key performance metrics: such as levelized cost of electricity (LCOE), efficiency, environmental impact, and cycle life. The results indicate LFP BESS as the optimal choice for both scenarios, achieving the lowest LCOE values (R4.05/kWh for 1.17 MWh and R4.25/kWh for 2.34 MWh), up to 34 percent (%) lower than Pb-acid BESS and 30% lower than VRFB. LFP also demonstrated significant advantages, including a high round-trip efficiency of up to 95%, a cycle life of 10-20 years, and a reduced environmental impact. Moreover, LFP requires 30% less installed capacity than Pb-acid, resulting in greater cost savings. The environmental emissions evaluation in this case study further demonstrated that a hybrid system with LFP achieved the lowest carbon dioxide (CO2) emissions, with reductions of 10.5% compared to Pb-acid and 23.4% compared to VRFB. While VRFB provides high durability and long-term efficiency, its higher LCOE and additional energy requirements make it less suitable for cost-sensitive, short-term applications. Consequently, the analysis identifies LFP batteries as the most techno-economically efficient option for large-scale stationary storage, underscoring their critical role of BESS in stabilizing energy supply, enhancing grid reliability, and reducing greenhouse gas emissions, pivotal for South Africa's sustainable energy transition.